Air-pump-controlling device.



H. W. MUNYAN.

AIR PUMP CONTROLLING DEVICE.

APPLICATION FILED AUG-24. l9l5.

Patented May 2, 1916.

UNITED STATES HARRY W. MUNYAN, OF WORCESTER, MASSACHUSETTS.

AIR-PUMP-CONTROLLING DEVICE.

Specification of Letters Patent.

Patented May 2, 1916.

Application filed August 24, 1915. Serial No. 47,201.

To all whom it may concern:

Be it known that I, HARRY W. MUNYAN, a citizen of the United States, residing at Worcester, in the county of Worcester and State of Massachusetts, have invented a new and useful Air-Pump-Controlling Device, of which the following is aspecification.

This invention relates to an air pump controlling device and is particularly adapted for use in connection with a compressed air supply system in which an electric motor is automatically controlled to maintain a predetermined pressure in a storage tank. Such supply systems are now commonly used for many purposes and particularly for supplying air for the inflation of the pneumatic tires 7 of motor vehicles. The usual system of this character is intended to operate without supervision and furthermore the air compressing mechanism is not designed for continuous operation. Arrangements are commonly-made for shutting off the motor and compressor when the tank pressure reaches 125 lbs., and provision is also made for starting the motor and compressor in operation whenever the pressure is reduced to 105 lbs. This range of pressure I have designated herein as normal tank pressures. Under normal conditions the motor and compressor will restore the maximum pressure in the tank in two or three minutes operation. It sometimes happens, however, that a slow leak will develop in the tank or in its connections or that the discharge valve of the tank is carelessly left partly open. Under these conditions the motor and compressor can only maintain the maximum pressure in the tank by substantially continuous operation, for which, as before stated, the mechanism is not designed or adapted.

- It is the object of my invention to provide a controlling device by which further operation of the motor shall be prevented after a predetermined period of operation has elapsed. In' the form of my invention herein illustrated I have attained this object by the provision of a heating chamber containing a fusible link which controls a circuit opening device in the motor circuit. The parts are so arranged that the circuit will be broken whenever the temperature within the heating chamber reaches a predetermined point.

It is, of course, well-known that the compression of air against heavy pressure raises the temperature of the compressed air to a substantial degree and I utilize this increase in temperature of the air as the controlling factor in determining the length of time during which the motor and compressor shall be permitted to operate. I have discovered that a fusible link suspended within a closed chamber and adjacent to the discharge pipe from the compressor to the storage tank will be melted whenever the compressor has been in operation for a period of time which is substantially constant for a given position of the link.

A further feature of my invention relates to the provision of means for varying the time during which the mechanism may operate, such variation being conveniently attained by changing the position of the link relatively to the discharge pipe.

Further features of my invention relate to certain arrangements and combinations of parts which will be hereinafter described and more particularly pointed out in the appended claims.

A preferred form of my invention is shown in the drawings, in which Figure 1 is a diagrammatic view of an air supply system having my invention applied thereto; Fig. 2 is a vertical sectional view through the heating chamber; Figs. 3 and l are side and edge elevations respectively of the fusible link; and Fig. 5 is an enlarged detail view of the link support.

Referring to Fig. 1, I have shown a motor 10 connected to operate an air compressor 11 having a discharge pipe 12 through which compressed air is delivered to a storage tank 13, all of this mechanism being of the usual type. The discharge pipe 12 in passing from the compressor 11 to the tank 13 passes through, or extends into a closed chamber 14:. The motor 10 is controlled by a main switch 15 to which are led the line wires 16 and 17, the wire 17 passing through the chamber 14: and being connected therein to the opposite ends of a knife switch 18 depending from the upper end of the chamber. Instead of a knife switch any other suitable or convenient circuit opening device may be substituted therefor. A fusible link 19 is suspended from a hook 20 within the chamber and provides a support for a wire or rod 21 extending downward through an opening in thelower end of the chamber and connected to a weight 22. Near its up per end, the wire 21 is loosely connected by a cord 23 to the outer end of the blade of the switch 18. The link 19 may be of any usual or suitable construction, the form shown in the drawings comprising two flat portions 19 and 19 having their ends overlapping and united by an alloy fusible at any desired temperature. I have found a link which will release at 160 F. to be suitable for this purpose. The link supporting hook 20 is provided with a series of notches 24 in any one of which the link may be positioned at the desired distance from the pipe 12.

lVith the construction and arrangement described, the motor and compressor will be automatically started in operation, by controlling devices not shown, whenever the tank pressure has fallen to a predetermined During the point, for instance 105 lbs. operation of the compressor the temperature within the chamber 14 will be gradually raised by the passage of the heated compressed air therethrough. When the tem perature within the chamber has been raised to the critical temperature of the link, the parts of the link will separate, permitting the weight 22 to fall and open the switch 18, thus stopping the motor 10. The device is ordinarily arranged so that the motor will be stopped after five minutes continuous operation, the link being placed in the notch 24: which is nearest to the pipe 12. With the link in the second notch the mechanism will be permitted to operate for ten minutes, and in the third notch for fifteen minutes. Any other periods of operation may be obtained by a change in the melting point of the link or in the positions of the notches 24 relative to the pipe 12.

l/Vhile I have shown only a single form of my invention in this application it will be evident that many modifications thereof can be readily devised by those skilled in the art without departing from the spirit and scope of my invention as set forth in the claims, and I do not wish to be otherwise limited to the details herein disclosed, but

lVhat I do claim is 1. In an air supply system, a motor, an electric circuit therefor, an air compressor driven by said motor, a storage tank, a discharge pipe connecting said compressor to said tank, and means to open said circuit and stop said motor after said motor has operated against normal tank pressures for a predetermined period of time.

2. In an .air supply system, a motor, an electric circuit therefor, an air compressor driven by said motor, a storage tank, a discharge pipe connecting said compressor to said tank, means to open said circuit and stop said motor after operation thereof against normal tank pressures for a predetermined period of time, and means to vary the length of said period.

3. In an air supply system, a motor, an electric circuit therefor, an air compressor driven by said motor, a storage tank, a discharge pipe connecting said compressor to said tank, a chamber through which said pipe extends, a thermal unit in said chamber, and means controlled thereby efiective to open said circuit and stop said motor after the motor has operated against normal tank pressures for a predetermined period of time. p p

a. In an air supply system, a motor, an electric circuit therefor, an air compressor driven by said motor, a storage tank, a discharge pipe connecting said compressor to said tank, a chamber through which said pipe extends, a thermal unit in said chamber, and means controlled by said unit, effective to open said circuit and stop said motor when the critical temperature of said thermal unit is attained in said chamber.

5. In an air supply system, a motor, an electric circuit therefor, an air compressor driven by said motor, a storage tank, a discharge pipe connecting said compressor to said tank, a chamber into which said pipe extends, a fusible link mounted in said chamber, a weight suspended by said link, and a circuit-opening device controlled by said weight.

6. In an air supply system, a motor, an electric circuit therefor, an air compressor driven by said motor, a storage tank, a discharge pipe connecting said compressor to said tank, a chamber into which said pipe extends, a fusible link mounted therein adjacent said discharge pipe, means to vary the heating action of said discharge pipe on said link, a circuit-opening device, and mechanism controlled by said link for oper ating said device.

7. In an air supply system, a motor, an electric circuit therefor, an air compressor driven by said motor, a storage tank, a discharge pipe connecting said compressor to said tank, a chamber through which said pipe extends, a switch in said circuit mounted in said chamber, a fusible link also mounted therein, and a weight attached to said switch and suspended from said link, fusion of said link through overheating of said chamber acting to release said weight and thereby open said switch.

8. In an air supply system, a motor, an electric circuit therefor, an air compressor driven by said motor, a storage tank, a discharge tank connecting said compressor to said tank, a chamber through which said pipe extends, a switch in said circuit mounted in said chamber, a fusible link, means to support said link at any one of a plurality of difierent distances from said pipe, and a Weight attached to said switch and suspended from said link, fusion of said link through overheating of said chamber 10 acting to release said weight and thereby open said switch.

In testimony whereof I have hereunto set my hand.

HARRY W. MUNYAN.

Gopies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents. Washington, D. O. 

